Adding "activate some layers" to ExportDocsAsPNG24.jsx

I'de like to add this code

function test(){      function tryLockLayer(name){         try{             lrs.getByName(name).locked = false;         } catch(e) {             return;         }     };         var doc=app.activeDocument;     var lrs = doc.layers;     tryLockLayer("Watermark");     tryLockLayer("All");     tryLockLayer("Fill");     tryLockLayer("No fill");     tryLockLayer("Background");     
}   
test();


function test1(){      function tryLockLayer(name){         try{             lrs.getByName(name).visible = false;         } catch(e) {             return;         }     };         var doc=app.activeDocument;     var lrs = doc.layers;     tryLockLayer("Watermark");     tryLockLayer("All");     tryLockLayer("Fill");     tryLockLayer("No fill");     tryLockLayer("Background");     
}   
test1();


function test2(){      function tryLockLayer(name){         try{             lrs.getByName(name).visible = true;         } catch(e) {             return;         }     };         var doc=app.activeDocument;     var lrs = doc.layers;     tryLockLayer("Watermark");     tryLockLayer("Fill");    tryLockLayer("Background");     
}   
test2();            
for (i=0; i<app.documents.length; i++)     {         var idoc = app.documents[i];         //alert("+"+idoc.path+"+");         if (idoc.path == "")             {                 file = File.saveDialog ("Save file...");                 idoc.saveAs (file);             }         else             {                 //alert(idoc.name);                 if (!idoc.saved)                     {                          idoc.save();                         idoc.saved = true;                     }             }     } 

in this script

/**********************************************************

ADOBE SYSTEMS INCORPORATED
Copyright 2005 Adobe Systems Incorporated
All Rights Reserved

NOTICE:  Adobe permits you to use, modify, and
distribute this file in accordance with the terms
of the Adobe license agreement accompanying it. 
If you have received this file from a source
other than Adobe, then your use, modification,
or distribution of it requires the prior
written permission of Adobe.

*********************************************************/

/**********************************************************


ExportDocsAsPNG24.jsx

DESCRIPTION

This sample gets files specified by the user from the
selected folder and batch processes them and saves them
as PDFs in the user desired destination with the same
file name.


**********************************************************/

// Main Code [Execution of script begins here]

// uncomment to suppress Illustrator warning dialogs
// app.userInteractionLevel = UserInteractionLevel.DONTDISPLAYALERTS;

var destFolder, sourceFolder, files, fileType, sourceDoc, targetFile, pngExportOpts;

// Select the source folder.
sourceFolder = Folder.selectDialog( 'Select the folder with Illustrator files you want to convert to PNG', '~' );

// If a valid folder is selected
if ( sourceFolder != null )
{
    files = new Array();    fileType = prompt( 'Select type of Illustrator files to you want to process. Eg: *.ai', ' ' );       // Get all files matching the pattern    files = sourceFolder.getFiles( fileType );       if ( files.length > 0 )    {        // Get the destination to save the files        destFolder = Folder.selectDialog( 'Select the folder where you want to save the converted PNG files.', '~' );        for ( i = 0; i < files.length; i++ )        {            sourceDoc = app.open(files[i]); // returns the document object                                               // Call function getNewName to get the name and file to save the pdf            targetFile = getNewName();                       // Call function getPNGOptions get the PNGExportOptions for the files            pngExportOpts = getPNGOptions();                       // Export as PNG            sourceDoc.exportFile( targetFile, ExportType.PNG24, pngExportOpts );                       sourceDoc.close(SaveOptions.DONOTSAVECHANGES);        }        alert( 'Files are saved as PNG in ' + destFolder );    }    else    {        alert( 'No matching files found' );    }
}


/*********************************************************

getNewName: Function to get the new file name. The primary
name is the same as the source file.

**********************************************************/

function getNewName()
{
    var ext, docName, newName, saveInFile, docName;    docName = sourceDoc.name;    ext = '.png'; // new extension for png file    newName = "";           for ( var i = 0 ; docName[i] != "." ; i++ )    {        newName += docName[i];    }    newName += ext; // full png name of the file       // Create a file object to save the png    saveInFile = new File( destFolder + '/' + newName );    return saveInFile;
}





/*********************************************************

getPNGOptions: Function to set the PNG saving options of the
files using the PDFSaveOptions object.

**********************************************************/

function getPNGOptions()
{
       // Create the PDFSaveOptions object to set the PDF options    var pngExportOpts = new ExportOptionsPNG24();             // Setting PNGExportOptions properties. Please see the JavaScript Reference    // for a description of these properties.    // Add more properties here if you like    pngExportOpts.antiAliasing = true;    pngExportOpts.artBoardClipping = true;    //pngExportOpts.horizontalScale = 100.0;    //pngExportOpts.matte = true;    //pngExportOpts.matteColor = 0, 0, 0;    pngExportOpts.saveAsHTML = false;    pngExportOpts.transparency = true;    //pngExportOpts.verticalScale = 100.0;    return pngExportOpts;
}

I need to activate some layers before export the PNG file.

Thanks

Ivan